1. Field of the Invention
The field of the invention relates to portable electrical appliances such as heaters having sensors for detecting objects that may interfere with their operation.
2. Description of the Related Art
Portable appliances, such as heaters, have been provided with various sensors for determining whether an object is too close to them. Such sensors may be in the form of mechanical detectors as disclosed in U.S. Pat. No. 4,906,818. Electronic sensors have also been used to shut off a heater in the event an object is too close to the heater outlet. U.S. Pat. No. 5,805,767 discloses the use of motion sensors for this purpose. U.S. Pat. No. 6,091,888 discloses the use of infrared or ultrasonic proximity detectors for detecting a stationary or moving object within a predetermined distance of the heater inlet or outlet.